Method, apparatus, program and system for migrating NAS system

ABSTRACT

In a state where the migration source NAS apparatus is continuously operated, a migration processing program confirms the update date and time of files stored in the migration source NAS apparatus, and migrates only the files that were not updated from a specific time to the start date and time of migration processing. Or, the migration processing program migrates the files stored in the migration source NAS apparatus sequentially from the oldest file. The migration performance is calculated based on the capacity and migration time of the migrated files, and the time required for migrating the non-migrated files is calculated based on the size and migration performance of the non-migrated files.

CROSS-REFERENCES

This application is a continuation application of U.S. application Ser.No. 12/188,487 filed on Aug. 8, 2008, now U.S. Pat. No. 8,019,726, theentirety of which is incorporated herein by reference.

This application relates to and claims priority from Japanese PatentApplication No. 2008-138853, filed on May 28, 2008, the entiredisclosure of which is incorporated herein by reference.

BACKGROUND

The present invention relates to a method, apparatus, program and systemfor migrating a NAS system.

A storage apparatus as represented by a disk array apparatus logicallypartitions the storage area of disk devices in the storage apparatus andprovides the partitioned storage areas to a host computer as volumes.This kind of storage apparatus is connected to a network, and the hostcomputer is connected to the storage apparatus via the network so as toaccess the volumes in a block format or a mainframe CKD format.Moreover, a NAS (Network Attached Storage) apparatus is known as onemeans for providing volume access in a file format to the host computervia the network. In a NAS apparatus, an OS (Operating System) and a filesystem are operated to retain information concerning the files anddirectories stored in the respective volumes provided by the storageapparatus, and implement the input and output of files according to arequest from the host computer.

If there is performance deterioration or capacity shortage in this kindof NAS apparatus, a method of migrating data of the existing NASapparatus to the new NAS apparatus to continue the operation may beconsidered.

As a conventional migration method of a storage apparatus, disclosed isa method of enabling access from the storage apparatus to be newlyinstalled to the existing storage apparatus, and the newly installedstorage apparatus processing a block access request from the hostcomputer while migrating block data from the existing storage apparatus(Japanese Patent Laid-Open Publication No. 2000-187608).

SUMMARY

With a migration method concerning a storage apparatus that providesblock access, a case is now considered regarding the foregoingconventional method where a NAS apparatus is respectively connected tothe existing storage apparatus and the newly installed storageapparatus. In the case of the migration method described in theforegoing patent document, when a file write request is received fromthe host computer during the migration processing, that file is writteninto the newly installed NAS apparatus and the newly installed NASapparatus writes the same file in the existing NAS apparatus. Thereby,even if the migration processing ends in a failure, operation can becontinued with the existing NAS apparatus. Nevertheless, with thismethod, there is a problem in that the file must be written into two NASapparatuses in response to a write request of a single file, and thewrite performance will deteriorate.

In light of the above, an object of the present invention is to providea method, apparatus, program and system for migrating a NAS systemconfigured from one or more NAS apparatuses and one or more storageapparatuses.

According to one embodiment of the present invention, provided is a filemigration method of an information system including a first NAS system,a second NAS system, and a computer for reading and writing a pluralityof files stored in the first NAS system. This file migration method ofthe information system includes a step of acquiring and storing firstattribute information including file names and update time informationconcerning a plurality of files to be stored in a designated directoryand below of the first NAS system, a step of acquiring and storingsecond attribute information including file names and update timeinformation concerning a plurality of files stored in the second NASsystem, a step of identifying a file to be copied from the first NASsystem to the second NAS system based on the difference between thestored first attribute information and second attribute information, anda prescribed rule concerning the update time information of the firstattribute information, and a step of copying the identified file fromthe first NAS system to the second NAS system.

As an example of a computer, there is a NAS client that accesses thefirst NAS system. Update time information is information that shows thetiming that the file was updated, and the form of presentation may beyear, month, day, hour, minute, second or day of the week, and it mayalso be the relative time from a certain reference time. It is therebypossible to avoid the performance deterioration of the writing requestedby the client computer. In addition, it is also possible to avoid therepeated execution of migration copy of files that are frequentlyupdated, and migration of the NAS system can be implemented in a shorttime.

As the prescribed rule, a file with old update time information of thefirst attribute information may be preferentially identified as a fileto be copied to perform efficient copying from a file with old updatetime which is less likely to be updated again. As another prescribedrule, based on a first time obtained by subtracting a predeterminedmigration exclusion update period from the execution time of the filemigration processing and the update time information of the firstattribute information, by identifying a file updated after the firsttime as a copy inhibition target, a file to be copied can be identifiedwith a smaller load than the former method. There is no particularlimitation on the execution sequence of the difference between the firstattribute information and the second attribute information (as examples,information showing files that exist in the first NAS system but do notexist in the second NAS system, and information showing that the fileexists in both NAS systems but the update of the file of the first NASsystem has not been reflected in the file of the second NAS system) andthe prescribed rule, and either the difference or prescribed rule may beexecuted first. The first attribute information and the second attributeinformation may be stored in either information system. In addition,since it is not necessary to constantly store the update timeinformation of all files concerning the designated directory of thefirst NAS system, for instance, a part of the update time informationand file names of a plurality of files may be temporarily stored as thefirst attribute information and the second attribute information in amigration computer (for example, a migration server or a part of the NASclient).

Moreover, if the NAS system is able to store files set with WORM, theacquired first attribute information includes information concerning aWORM setting of a plurality of files stored in a designated directoryand below of the first NAS system, and the step of copying theidentified file from the first NAS system to the second NAS system mayalso include a step of setting a WORM to the file copied to the secondNAS system according to information concerning the WORM setting includedin the first attribute information. Migration of a NAS system includingfiles set with WORM is thereby enabled.

Further, the acquired second attribute information includes informationconcerning the WORM setting of the file copied to the second NAS system,and the file migration method may further comprise a step of identifyinga file set with WORM from the second attribute information, and a stepof excluding the identified file set with WORM from the acquisitiontarget of the first attribute information. Since the files set with WORMwill not be updated in the first NAS system, the migration process canbe sped up since the amount of information to be acquired from the firstNAS system can be reduced.

In addition, the step of copying the identified file from the first NASsystem to the second NAS system includes a step of recording the copyingtime and file size of the copied file, and the file migration method mayfurther comprise a step of identifying the total file size concerningfiles to be copied before the end of migration among a plurality offiles stored in a designated directory and below of the first NASsystem, and a step of providing migration period information based onthe copying time, the file size and the total file size. Thereby, theadministrator who uses the migration method of the present inventionwill be able to estimate the time required until the completion ofmigration. Although a method of displaying a display device of amigration server can be considered as a method of providing migrationperiod information, migration period information may be sent to anothercomputer for displaying this on a different computer based on suchinformation, or the migration period information may be sent to aprogram that is being executed in another computer.

Although the foregoing invention may be executed with any component ofthe information system, in particular, if the present invention isexecuted with the second NAS system, acquisition of the second attributeinformation and file copy can be performed at high speed. In addition,by executing the present invention with a migration computer connectedto the first NAS system and the second NAS system, the present inventioncan also be applied to a NAS system that is not equipped with amigration function, and the load associated with the migration process(for instance, acquisition and storage of attribute information andapplication of prescribed rules) can be alleviated.

The present invention is able to avoid the deterioration in writeperformance of the NAS apparatus associated with migration.

DESCRIPTION OF DRAWINGS

FIG. 1 is a diagram schematically showing the configuration of a storagenetwork system of the first embodiment adopting the NAS apparatusmigration method according to the present invention;

FIG. 2 is a diagram showing an example of a format of a NAS managementtable;

FIG. 3 is a diagram showing an example of a format of a schedule tableaccording to the first embodiment and the third embodiment;

FIG. 4 is a diagram schematically showing the configuration of amigration source NAS apparatus, and of a migration destination NASapparatus according to the first embodiment and the second embodiment;

FIG. 5 is a processing flow of a migration processing startup processingprogram;

FIG. 6 is a processing flow of the migration processing programaccording to the first embodiment and the third embodiment deletingfiles from the migration destination NAS apparatus which do not exist inthe migration source NAS apparatus;

FIG. 7 is a processing flow of the migration processing programaccording to the first embodiment and the third embodiment for migratingfrom the migration source NAS apparatus to the migration destination NASapparatus;

FIG. 8 is a processing flow of the migration processing programaccording to the first embodiment and the third embodiment migratingdirectories from the migration source NAS apparatus to the migrationdestination NAS apparatus;

FIG. 9 is a processing flow of the migration processing programaccording to the first embodiment and the third embodiment migratingfiles from the migration source NAS apparatus to the migrationdestination NAS apparatus;

FIG. 10 is an example of a format of an execution result log;

FIG. 11 is a processing flow of a migration period estimate processingprogram according to the first embodiment and the third embodiment;

FIG. 12 is a diagram schematically showing the configuration of astorage network system of the second embodiment adopting the NASapparatus migration method according to the present invention;

FIG. 13 is a diagram showing an example of a schedule table according tothe second embodiment and the fourth embodiment;

FIG. 14 is a diagram showing an example of a file management table;

FIG. 15 is a processing flow of the migration processing programaccording to the second embodiment and the fourth embodiment deletingfiles from the migration destination NAS apparatus that do not exist inthe migration source NAS apparatus;

FIG. 16 is a processing flow of the migration processing programaccording to the second embodiment and the fourth embodiment formigrating from the migration source NAS apparatus to the migrationdestination NAS apparatus;

FIG. 17 is a diagram schematically showing the configuration of astorage network system of the third embodiment and the fourth embodimentadopting the NAS apparatus migration method according to the presentinvention;

FIG. 18 is a diagram schematically showing the configuration of amigration destination NAS apparatus according to the third embodiment;

FIG. 19 is a diagram schematically showing the configuration of amigration destination NAS apparatus according to the fourth embodiment;and

FIG. 20 is a diagram schematically showing a migration routine based onthe NAS apparatus migration method according to the present invention.

DETAILED DESCRIPTION

Embodiments of the present invention are described below.

First Embodiment

FIG. 1 is a configuration example of a system schematically showing astorage network system adopting an embodiment of the present invention.

As shown in FIG. 1, the storage network system of the present embodimentcomprises a migration server 1, at least one migration source NASapparatus 2 a, a storage apparatus 50 a connected to the migrationsource NAS apparatus 2 a, at least one migration destination NASapparatus 50 b, a storage apparatus 3 b connected to the migrationdestination NAS apparatus 2 b, a plurality of NAS clients 100 thatimplement file access to the migration source NAS apparatus 2 a, and anetwork 3 for connecting the migration server 1 to the copy source NASapparatus 2 a, the copy destination NAS apparatus 2 b and the NAS client100.

The migration server 1 comprises a memory 7, a CPU 8, an I/O port 9 forconnecting to the network 3, an input device 10 for connecting akeyboard 5 and a mouse 6, an output device 11 for connecting a displaydevice 4, and an internal bus 12 for connecting the foregoing components7 to 11. The memory 7 stores a communication control processing program16 for communicating with the communication protocol of the network 3, anetwork file system 13 that performs access control to the migrationsource NAS apparatus 2 a and the migration destination NAS apparatus 2b, a migration processing program 14 for implementing the NAS apparatusmigration method of the present invention, a migration processingstartup processing program 15 for starting up the migration processingprogram 14, and a migration period estimate processing program 17 forestimating the migration period. The CPU 8 executes these programs. Thememory 7 additionally stores a schedule table 30 storing a schedule forthe migration processing startup processing program 15 to start up themigration processing program 14, a NAS management table 20 to be used bythe migration processing program 14, and an execution result log 40 foroutputting the migration result of the migration processing program 14.Although not shown, the memory 7 also stores the operating system.

The storage apparatuses 50 a, 50 b include at least one I/O port 51 forconnecting to the migration source NAS apparatus 2 a and the migrationdestination NAS apparatus 2 b, a controller 52 for performing control inthe storage apparatus, and at least one disk device 60 configuring atleast one volume 53. The volume 53 is a volume for providing a filesystem to the user of the NAS apparatuses 2 a, 2 b, and stores files andtheir attribute information.

The NAS client 100 is a standard personal computer with an operatingsystem running thereon and, although not shown, an application programused by the network file system or NAS for accessing the share directoryprovided by the NAS apparatus is also running thereon. The NAS client100 implements file access to the share directory provided by themigration source NAS apparatus 2 a until the migration processing fromthe migration source NAS apparatus 2 a to the migration destination NASapparatus 2 b is complete, and, when such migration is complete, itimplements file access to the share directory provided by the migrationdestination NAS apparatus 2 b.

Meanwhile, the time required for migrating the NAS apparatus will becomelonger in proportion to the amount of data stored in the migrationsource NAS apparatus 2 a. In addition, depending on the load on themigration source NAS apparatus 2 a caused by the migration processing,the access performance of the NAS client 100 to the migration source NASapparatus 2 a may deteriorate. Thus, the NAS apparatus migration methodof the present invention implements migration processing on a dailybasis only during the time frame in which the access from the NAS client100 to the migration source NAS apparatus 2 a is low (for instance, onlyat night). As a result, migration will progress on a daily basis.Nevertheless, as described above, since the NAS client 100 accesses theshare directory provided by the migration source NAS apparatus 2 a,there are cases where a file that was once migrated is updated. Theoutline of processing of the NAS apparatus migration method of thepresent invention to be performed to files that are updated during themigration period is now explained with reference to FIG. 20.

FIG. 20 is a diagram showing the outline of the migration routineaccording to the NAS apparatus migration method of the presentinvention. As described above, the present invention implementsmigration to the newly installed NAS apparatus while continuing theoperation of the existing NAS apparatus in order to avoid deteriorationin the write performance. Specifically, the host computer reads andwrites files from and into the existing NAS apparatus, and the newlyinstalled NAS apparatus capable of accessing the existing NAS apparatusimplements the migration processing. Otherwise, a computer that iscapable of accessing the existing NAS apparatus and the newly installedNAS apparatus implements the migration processing. In the foregoingcase, since the file write request from the host computer is processedonly with the existing NAS apparatus, it is possible to avoid theproblem of deterioration in the write performance. Nevertheless, sincefiles of the existing NAS apparatus will be updated, it is necessary torepeatedly perform the migration processing. Here, if numerous filesthat were once migrated are updated in the existing NAS apparatus, thereis a problem in that the numerous updated files must be migrated onceagain and, during that period, the migration of non-migrated files willnot be performed, and the migration processing will not progress.

The example of FIG. 20 shows a measure to be taken against the foregoingproblem, and the migration server 1 migrates, during the firstmigration, files “A1” and “B1” among the files 201 stored in the sharedirectory 200 of the migration source NAS apparatus 2 a to the sharedirectory 200 of the migration destination NAS apparatus 2 b. After thefirst migration is complete, the NAS client 100 updates the file “A1,”“B1” and “C1” of the share directory 200 of the migration source NASapparatus 2 a, and the foregoing files become files “A2,” “B2” and“C2.”Subsequently, upon implementing the second migration processing,the migration server 1 does not implement the migration of the files“A2,” “B2” and “C2” that were updated after the completion of the firstmigration processing, and implements the files “D1” and “E1.” Thereby,when implementing the migration of the migration source NAS apparatus 2a in which the same files are updated daily, migration of only theupdated files on a daily basis can be avoided, and it is therebypossible to perform migration efficiently.

FIG. 2 is a diagram showing the registered contents of the NASmanagement table 20. As shown in FIG. 2, the NAS management table 20comprises a field 21 for registering the ID for identifying theregistration information, a field 22 for registering the IP address ofthe migration source NAS apparatus 2 a, a field 23 for registering theshare directory name to be migrated from the migration source NASapparatus 2 a, a field 24 for registering the IP address of themigration destination NAS apparatus 2 b, and a field 25 for registeringthe share directory name of the migration destination NAS apparatus 2 bto which the contents of the share directory of the field 23 aremigrated.

For instance, from the entry of the field 21 in which the value is“ID-001,” it possible to tell that the contents of the share directory“Share1” of the migration source NAS apparatus 2 a having the IP addressof “192.168.10.11” will be migrated to the share directory “Share1” ofthe migration destination NAS apparatus 2 b having the IP address of“192.168.10.21.”

FIG. 3 shows an example of the registered contents of the schedule table30. The schedule table 30 registers the schedule for implementing themigration processing based on the entries of the migration source NAS 2a and the migration destination NAS 2 b registered in the NAS managementtable 20. As shown in FIG. 3, the schedule table 30 comprises a field 31for registering the ID for identifying the pair of the migration sourceNAS apparatus 2 a and the migration destination NAS 2 b to be subject tothe registered information; that is, the ID registered in the field 21of the NAS management table 20, a field 32 for registering the date andtime for starting the migration processing, a field 33 for registeringthe date and time for ending the migration processing, and a field 34for registering the condition of the update date and time of the file tobe migrated. If there is no designation in the field 33, this shows thatthe migration processing will not be ended midway. In other words,migration processing will be implemented until the migration of allfiles is complete. Moreover, if the value of the field 34 is “0,” thisshows that the file will be migrated regardless of the update date andtime of such file.

For instance, with the first entry of FIG. 3, the value of the field 31is “ID-001,” and, from the entry in which the value of the field 21 ofthe NAS management table 21 is “ID-001,” it is possible to tell thatthis is a schedule for migrating the contents of the share directory“Share1” of the migration source NAS apparatus 2 a having an IP addressof “192.168.10.11” to the share directory “Share1” of the migrationdestination NAS apparatus 2 b having an IP address of “192.168.10.21,”migration will start at 20:00 on Jan. 2, 2008 and migration will end at7:00 on Jan. 3, 2008. In addition, it is also possible to tell thatfiles that are not updated within 24 hours will not be migrated.

The fifth entry of FIG. 3 has no designation in the field 33; that is,there is no designation regarding the migration end date and time. Inthis case, it is possible to tell that the migration processing will notbe ended until the migration processing of all files is complete. Inaddition, the value of the field 34 is “0,” and it is possible to tellthat the migration of files is terminated by migration all filesregardless of the update date and time of such files.

FIG. 4 is a diagram schematically showing a configuration example of themigration source NAS apparatus 2 a and the migration destination NASapparatus 2 b. As shown in FIG. 4, the NAS apparatuses 2 a, 2 b comprisea memory 70, a CPU 71, at least one I/O port 72 for connecting to thestorage apparatuses 50 a, 50 b, a management port 73, and an internalbus 74 for connecting the foregoing components 70 to 73. The memory 70stores a communication control processing program 75 for communicatingwith a communication protocol of the network 3, an NFS/CIFS serverprocessing program 76 that provides a function for the host computer toaccess the volumes provided by the NAS apparatuses 2 a, 2 b, and aNAS-OS 77 for implementing processing according to the contents readfrom and written into the files that the NFS/CIFS server processingprogram 76 received from the host computer. The CPU 71 executes theseprograms.

The processing routine of the migration processing startup processingprogram 15 is now explained with reference to FIG. 5. FIG. 5 shows theprocessing flow of the migration processing startup processing program15.

The migration processing startup processing program 15 reads theschedule table 30 at S1101, confirms the start date and time of themigration processing program 14 from the field 31 of the schedule table30 at S1102, and starts up the migration processing program 14 at theconfirmed start date and time (S1103). Here, the IP address of themigration source NAS apparatus 2 a and the migration destination NAS 2 bacquired from the NAS management table 20, the share directory name, andthe value of the field 34 of the schedule table 30 are designated as thestartup parameter of the migration processing program.

Subsequently, [the migration processing startup processing program 15]confirms whether the end date and time of the migration processingprogram 14 has been set in the field 33 of the schedule table 30 atS1104, ends the processing if the end date and time has not been set,and proceeds to S1105 if the end date and time has been set. At S1105,the migration processing startup processing program 15 acquires the enddate and time set in the field 33 of the schedule table 30, stopsmigration processing program 14 at the acquired end date and time(S1105), and then ends the processing.

Incidentally, the processing from S1102 to S1105 is executed in parallelfor each entry registered in the schedule table 30.

The processing routine of the migration processing program 14 in thisembodiment is now explained with reference to FIG. 6 to FIG. 10.

FIG. 6 is a processing flow showing the processing routine where, as thepreprocessing of the migration processing, the migration processingprogram 14 deletes files, which were deleted from the migration sourceNAS apparatus 2 a and exist only in the migration destination NASapparatus 2 b, from the migration destination NAS 2 b.

Foremost, the migration processing program 14, at S1201, mounts a sharedirectory of the migration source NAS apparatus 2 a designated by themigration processing startup processing program 15 with a certaindirectory (hereinafter simply referred to as “SRC”) of the migrationserver 1 as the mount point, and at S1202, mounts a share directory ofthe migration destination NAS apparatus 2 b designated by the migrationprocessing startup processing program 15 with a different directory(hereinafter simply referred to as “DST”) of the migration server 1 asthe mount point. Subsequently, the migration processing program 14acquires a list of files and directories in “SRC” at S1203, and acquiresa list of files and directories in “DST” at S1204. At S1205, themigration processing program 14 compares the list of files anddirectories acquired at S1203 and S1204, and deletes from “DST” thefiles and directories only existing in “DST” at S1206. Subsequently, atS1207, the migration processing program 14 sets “SRC” as “source Dir”and sets “DST” as “destination Dir,” and thereafter implements migrationprocessing at S1208. Details concerning the migration processing will beexplained with reference to FIG. 7. Although the list of directories(including at least the file name and update time of each file) acquiredat S1203 and S1204 may be temporarily or permanently stored in one ofthe apparatuses of the information system, it is preferably stored inthe migration server.

FIG. 7 is a processing flow showing the processing routine where themigration processing program 14 of this embodiment migrates the filesstored in the file system of the migration source NAS apparatus 2 a tothe file system of the migration destination NAS apparatus 2 b. In thisflow, recursive processing is performed by sequentially changing theforegoing values with the values of “source Dir” and “destination Dir”set at S1207 of FIG. 6 as the top directory.

Foremost, the migration processing program 14, at S1301, confirmswhether there is a directory in the “source Dir” which was notpreviously subject to the processing of S1302 (this directory ishereinafter sometimes referred to as an “unprocessed directory”). Ifthere is a directory that was not subject to the processing of S1302 asa result of the confirmation at S1301, the migration processing program14 designates that directory and implements S1302, and proceeds to S1303if there is no directory that was not subject to the processing ofS1302.

At S1302, the migration processing program 14 creates a directory, whichexists in “source Dir” but does not exist in “destination Dir,” in“destination Dir” and changes the directory to be processed; that is,changes “source Dir” and “destination Dir.” Details of this processingwill be explained with reference to FIG. 8. After changing “source Dir”and “destination Dir” at S1302, the migration processing program 14performs the processing of S1301 to the changed “source Dir” and“destination Dir.”

At S1303, the migration processing program 14 confirms whether there isa file in “source Dir” which was not subject to the migration processingof S1304 after being previously created or updated (this kind of file ishereinafter sometimes referred to as an “unprocessed file”). If there isa file that was not subject to the processing of S1304 as a result ofthe confirmation at S1303, the migration processing program 14designates that file and implements S1304, and proceeds to S1305 ifthere is no file that was not subject to the processing of S1304.

At S1304, the migration processing program 14 migrates the file from“source Dir” to “destination Dir,” and then proceeds to S1303. Detailsregarding the processing at S1304 will be explained later with referenceto FIG. 9.

At S1305, the migration processing program 14 confirms whether “sourceDir” and “SRC” are the same directory. If “source Dir” and “SRC” are thesame directory as a result of the confirmation at S1305, the migrationprocessing program 14 ends the processing. Meanwhile, if “source Dir”and “SRC” are different directories, the migration processing program 14implements S1306 and S1307, and thereafter proceeds to S1301.

At S1306, the higher-level directory of “source Dir” is set as “sourceDir.” For instance, if “source Dir” is “/aaa/bbb/ccc,” “source Dir” isset as “/aaa/bbb.” At S1307, the higher-level directory of “destinationDir” is set as “destination Dir.”

As a result of the foregoing processing, migration of directories andfiles in the directory of the migration source NAS apparatus 2 a to theshare directory of the migration destination NAS apparatus 2 b iscomplete.

The processing at S1302 of FIG. 7 is now explained in detail withreference to FIG. 8. FIG. 8 is a processing flow for the migrationprocessing program 14 of this embodiment to create a directory existingin “source Dir,” which is designated upon implementing S1302 of FIG. 7,in “destination Dir.”

The migration processing program 14, at S1401, acquires the designateddirectory from “source Dir.” Subsequently, at S1402, the migrationprocessing program 14 confirms whether the designated directory existsin “destination Dir,” and proceeds to S1404 if the designated directoryexists in “destination Dir.” Meanwhile, if the designated directory doesnot exist in “destination Dir,” the migration processing program 14, atS1403, creates that directory in “destination Dir” and then proceeds toS1404. At S1404, the migration processing program 14 sets the directoryacquired at S1401 as “source Dir,” and sets a directory of “destinationDir” that is identical to that directory as “destination Dir.”

Details regarding the processing at S1304 of FIG. 7 are now explainedwith reference to FIG. 9. FIG. 9 is a processing flow for the migrationprocessing program 14 of this embodiment to migrate the files existingin “source Dir,” which is designated upon implementing S1304 of FIG. 7,to “destination Dir.”

The migration processing program 14, at S1501, confirms whether thevalue of the field 34 of the schedule table 30 designated by themigration processing startup processing program 15 is “0,” and proceedsto S1505 of such value is “0.” Meanwhile, if the value is other than“0,” the migration processing program 14 proceeds to S1502.

At S1502, the migration processing program 14 acquires the update dateand time of the designated file. Subsequently, at S1503, the migrationprocessing program 14 confirms whether the update date and time of thedesignated file satisfies the value of the field 34 of the scheduletable 30; that is, the condition of the update date and time of themigration-target file designated by the migration processing startupprocessing program 15 during the startup of the migration processingprogram 14. For example, if the migration processing program 14 wasstarted up according to the schedule of the first entry of the scheduletable 30, the migration processing program 14 confirms whether an updatehas occurred before “20:00 on Jan. 1, 2008” obtained by subtracting “24hours,” which is the value of the field 34, from “20:00 on Jan. 2, 2008”as the migration start date and time regarding the designated file.

The migration processing program 14 proceeds to S1505 if the designatedfile satisfies a prescribed condition defined in the schedule table 30or defined by a user as a result of S1503, and proceeds to S1504 if thedesignated file does not satisfy the prescribed condition.

At S1504, the migration processing program 14 confirms whether the filein which the update date and time was confirmed is a non-modifiablefile; that is, whether it is a so-called WORM (Write Only Read Many)file. If the file is a WORM file as a result of S1504, the migrationprocessing program 14 proceeds to S1505. Meanwhile, if the file is not aWORM file, at S1508, the migration processing program 14 outputs amessage to the execution result log 40 to the effect that the designatedfile has been excluded from migration, and then ends the processing.Incidentally, WORM is a function that is used for guaranteeing that thedigital file submitted to the court or in an audit has not been updated.As one method of realizing WORM, the NAS apparatus denies the update ordeletion request of a file once set with WORM issued by a user of theNAS client or the NAS apparatus, and also denies permanently or for apredetermined period of time a cancellation request of the WORM settingfrom the user of the NAS client or the NAS apparatus. In addition, WORMcan also be realized by guaranteeing that the foregoing modification ordeletion will not be carried out for at least a given period of time.

At S1505, the migration processing program 14 acquires a file and theattribute information and time stamp of such file from “source Dir,” andtemporarily stores these in the memory 7. Subsequently, at S1506, themigration processing program 14 confirms whether a file that isidentical to the file stored in the memory 7 at S1505 exists in“destination Dir.” Here, whether the attribute information and timestamp of the file are identical is also confirmed. If the same fileexists in “destination Dir” as a result of S1506, the migrationprocessing program 14, at S1508, outputs the designated file and amessage to the effect that the same file exists in “destination Dir” tothe execution result log 40, and then ends the processing. A log showingthat the same file exists may or may not be output.

If a same file does not exist in “destination Dir” as a result of S1506,the migration processing program 14, at S1507, copies the filetemporarily stored in the memory 7 to “destination Dir.” Here, theattribute information (system file attribute, read-only attribute,encryption attribute, WORM attribute, etc.) and the time stamp (createddate and time, update date and time, last access date and time) of thefile are also copied, and the file and the attribute information andtime stamp of that file are deleted from the memory 7. At S1508, themigration processing program 14 outputs a message to the effect that thefile has been copied to “destination Dir” to the execution result log40, and then ends the processing. Although the copying performed atS1506 may initially target all file data, if the same file has alreadybeen copied to the migration destination NAS apparatus 2 b, a part ofthe file data including the changes may be copied.

After completing the migration of all files from the migration sourceNAS apparatus 2 a to the migration destination NAS apparatus 2 b basedon the foregoing processing, by setting the IP address of the migrationsource NAS apparatus 2 a to the migration destination NAS apparatus 2 b,operation with the migration destination NAS apparatus 2 b can bestarted without having to change the setting of the NAS client 100.

FIG. 10 shows an example of the execution result log 40. Output to theexecution result log 40 are the status showing whether the migrationprocessing program 14 copied the file based on the migration result ofthe file existing in the share directory of the migration source NASapparatus 2 a (Copied), excluded the file because the update date andtime of the file did not satisfy a prescribed condition (Excluded), orskipped the file since the same file exists in the share directory ofthe migration destination NAS apparatus 2 b (Same), and the file nameand file size of the target file. In addition, if the status is“Copied,” the time required for the copying process is output as thecopying time.

For example, FIG. 10 shows that the file “/dir1/file1” has a file sizeof “1,024,” was copied, and the copying time was “2” hours. FIG. 10 alsoshows that the file “/dir1/file3” has a file size of “2,048” and wasexcluded from migration.

The processing routine of the migration period estimate processingprogram 17 is now explained with reference to FIG. 11. FIG. 11 is aprocessing flow for the migration period estimate processing program 17to estimate the time required for migrating the non-migrated files basedon the contents of the execution result log 40.

Foremost, the migration period estimate processing program 17, at S1601,sets the “migration time,” “migration total,” and “exclusion total” to“0,” and acquires one log from the execution result log 40 at S1602.Subsequently, at S1603, the migration period estimate processing program17 confirms the type of log, or the status of the log. If the status ofthe log is “Same” as a result of S1603, the migration period estimateprocessing program 17 proceeds to S1607. If the status of the log is“Excluded” as a result of S1603, the migration period estimateprocessing program 17, at S1604, adds the value of the file size of thelog to the “exclusion total,” and then proceeds to S1607. If the statusof the log is “Copied” as a result of S1603, the migration periodestimate processing program 17, adds the value of the file size of thelog to the “migration total” at S1605, adds the value of the copyingtime of the log to the “migration time” at S1606, and then proceeds toS1607.

At S1607, the migration period estimate processing program 17 confirmswhether the processing was performed to all logs of the execution resultlog 40, and proceeds to S1608 if the processing was performed to alllogs. Meanwhile, if the processing was not performed to all logs, themigration period estimate processing program 17 proceeds to S1602, andperforms the processing to the subsequent log.

At S1608, the migration period estimate processing program 17 sets avalue obtained by dividing the value of “migration total” by the valueof “migration time” as the “copy performance.” Subsequently, at S1609,the migration period estimate processing program 17 sets a valueobtained by dividing the value of “exclusion total” by the value of“copy performance” as the “migration period.” Finally, at S1610, themigration period estimate processing program 17 outputs the values of“copy performance,” “migration period” and “exclusion total” to thedisplay device 4.

In the first embodiment of the NAS apparatus migration method accordingto the present invention, the migration server 1 migrates files, otherthan the files that were updated from a certain specific date and timeto the migration start date and time among the files stored in the sharedirectory of the migration source NAS apparatus 2 a, to the sharedirectory of the migration destination NAS apparatus 2 b. Thus, whenrepeatedly migrating the NAS apparatus on a daily basis based on themigration method of the present invention in a state of continuing theoperation of the migration source NAS apparatus 2 a, the files that areupdated daily can be excluded from the migration target, and there is aparticular effect of being able to quicken the migration progress ifthere is locality in the files to be updated by the NAS client.Moreover, the migration performance is calculated based on the file sizeof the migrated file and the time required for the migration, and thetime required for migrating the non-migrated files is calculated basedon the file size of the non-migrated files and the migrationperformance. Thus, it is possible to estimate the time required tomigrate the non-migrated files (files excluded from migration). Further,since migration processing is implemented while continuing the operationof the migration source NAS apparatus, the latest files will constantlybe stored in the migration source NAS apparatus. Thus, the operation ofthe migration source NAS apparatus can be easily resumed even if themigration processing is unsuccessful due to a failure or the like.

Second Embodiment

The second embodiment of the present invention is now explained withreference to FIG. 12 to FIG. 16. Explanation regarding the subjectmatter that is common with the first embodiment is omitted.

FIG. 12 is a configuration example of a system schematically showing astorage network system adopting the second embodiment of the presentinvention.

As shown in FIG. 12, the storage network system of this embodimentcomprises a migration server 1, at least one migration source NASapparatus 2 a, a storage apparatus 50 a connected to the migrationsource NAS apparatus 2 a, at least one migration destination NASapparatus 50 b, a storage apparatus 3 b connected to the migrationdestination NAS apparatus 2 b, a plurality of NAS clients 100 forperforming file access to the migration source NAS apparatus 2 a, and anetwork 3 for connecting the migration server 1 to the copy source NASapparatus 2 a, the copy destination NAS apparatus 2 b and the NAS client100.

The migration server 1 comprises a memory 7, a CPU 8, an I/O port 9 forconnecting to the network 3, an input device 10 for connecting akeyboard 5 and a mouse 6, an output device 10 for connecting a displaydevice 4, and an internal bus 12 for connecting the foregoing components7 to 11. The memory 7 stores a communication control processing program16 for communicating with the communication protocol of the network 3, anetwork file system 13 that performs access control to the migrationsource NAS apparatus 2 a and the migration destination NAS apparatus 2b, a migration processing program 14 for implementing the NAS apparatusmigration method of the present invention, and a migration processingstartup processing program 15 for starting up the migration processingprogram 14. The CPU 8 executes these programs. The memory 7 additionallystores a schedule table 80 storing a schedule for the migrationprocessing startup processing program 15 to start up the migrationprocessing program 14, a NAS management table 20 to be used by themigration processing program 14, an execution result log 40 foroutputting the migration result of the migration processing program 14,and a file management table 90 storing a list of files stored in theshare directory of the migration source NAS apparatus 2 a. Although notshown, the memory 7 also stores the operating system.

The storage apparatuses 50 a, 50 b include at least one I/O port 51 forconnecting to the migration source NAS apparatus 2 a and the migrationdestination NAS apparatus 2 b, a controller 52 for performing control inthe storage apparatus, and at least one disk device 60 configuring atleast one volume 53. The volume 53 is a volume for providing a filesystem to the user of the NAS apparatuses 2 a, 2 b, and stores files andtheir attribute information.

FIG. 13 shows an example of the registered contents of the scheduletable 80. The schedule table 80 registers the schedule for implementingthe migration processing based on the entries of the migration sourceNAS 2 a and the migration destination NAS 2 b registered in the NASmanagement table 20. As shown in FIG. 13, the schedule table 80comprises a field 81 for registering the ID for identifying the pair ofthe migration source NAS apparatus 2 a and the migration destination NAS2 b to be subject to the registered information; that is, the IDregistered in the field 21 of the NAS management table 20, a field 82for registering the date and time for starting the migration processing,and a field 83 for registering the date and time for ending themigration processing. If there is no designation in the field 83, thisshows that the migration processing will not be ended midway. In otherwords, migration processing will be implemented until the migration ofall files is complete (i.e., until the file migration is terminated).

For instance, with the first entry of FIG. 13, the value of the field 81is “ID-001,” and, from the entry in which the value of the field 21 ofthe NAS management table 21 is “ID-001,” it is possible to tell thatthis is a schedule for migrating the contents of the share directory“Share1” of the migration source NAS apparatus 2 a having an IP addressof “192.168.10.11” to the share directory “Share1” of the migrationdestination NAS apparatus 2 b having an IP address of “192.168.10.21,”migration will start at 20:00 on Jan. 2, 2008 and migration will end at7:00 on Jan. 3, 2008. Since the fourth entry of FIG. 13 has nodesignation in the field 83, it is possible to tell that the migrationprocessing will not be ended until the migration processing of all filesis complete.

FIG. 14 is a diagram showing an example of the registered contents ofthe file management table 90. The files stored in the share directory ofthe migration source NAS apparatus 2 a are registered in the filemanagement table 90 in chronological order of the update date and time.In the example of FIG. 14, “/dir1/file2” has the oldest update date andtime, and “/dir1/dir2/dir3/file1” is the second oldest file.

The processing routine of the migration processing program 14 in thisembodiment is now explained with reference to FIG. 15 and FIG. 16.Incidentally, since the processing routine of the migration processingstartup processing program 15 for starting up the migration processingprogram 14 is the same as the first embodiment, the explanation thereofis omitted.

FIG. 15 is a processing flow showing the processing routine where, asthe preprocessing of the migration processing, the migration processingprogram 14 deletes files, which were deleted from the migration sourceNAS apparatus 2 a and exist only in the migration destination NASapparatus 2 b, from the migration destination NAS 2 b, and creates afile management table. Foremost, the migration processing program 14, atS2101, mounts a share directory of the migration source NAS apparatus 2a designated by the migration processing startup processing program 15on “SRC,” and at S2102, mounts a share directory of the migrationdestination NAS apparatus 2 b designated by the migration processingstartup processing program 15 on “DST.” Subsequently, the migrationprocessing program 14 acquires a list of files and directories in “SRC”at S2103, and acquires a list of files and directories in “DST” atS2104. At S2105, the migration processing program 14 compares the listof files and directories acquired at S2103 and S2104, and deletes from“DST” the files and directories only existing in “DST” at S2106.Subsequently, at S2107, the migration processing program 14 sorts thecontents of the list of files and directories in “SRC” in chronologicalorder of the update date and time, outputs the sorted contents to thefile management table 90, and thereafter implements the migrationprocessing at S2108. Details regarding the migration processing will beexplained with reference to FIG. 16.

FIG. 16 is a processing flow showing the processing routine for themigration processing program 14 of this embodiment to migrate the filesstored in the file system of the migration source NAS apparatus 2 a tothe file system of the migration destination NAS apparatus 2 b.

Foremost, the migration processing program 14, at S2201, acquires thefile name from the file management table 90, and, at S2202, extracts thedirectory name from the file name acquired at S2201. Subsequently, atS2203, the migration processing program 14 confirms whether thedirectory of the directory name extracted at S2202 exists in “DST.” Ifthe directory exists in “DST” as a result of S2202, the migrationprocessing program 14 proceeds to S2205. Meanwhile, if the directorydoes not exist in “DST,” the migration processing program 14, at S2204,creates the directory of the directory name extracted at S2202 in “DST,”and thereafter proceeds to S2205.

At S2205, the migration processing program 14 acquires the file of thefile name acquired at S2201 and the attribute information and time stampof such file, and temporarily stores these in the memory 7.Subsequently, at S2206, the migration processing program 14 confirmswhether the same file as the file stored in the memory 7 at S2205 existsin “DST.” Here, whether the attribute information and time stamp of thefile are the same is also confirmed. If the same file exists in “DST” asa result of the confirmation at S2206, the migration processing program14, at S2208, outputs a message to the effect that the same file existsin “DST” to the execution result log 40, and then proceeds to S2209.

If the same file does not exist in “DST” as a result of the confirmationat S2206, the migration processing program 14, at S2207, copies the filethat was temporarily stored in the memory 7 at S2205 to “DST,” anddeletes the file and the attribute information and time stamp of suchfile from the memory 7. Here, the attribute and time stamp of the fileare also copied. At S2208, the migration processing program 14 outputs amessage to the effect that the file has been migrated to the executionresult log 40, and then proceeds to S2209.

At S2209, the migration processing program 14 confirms whether there isan unprocessed file name in the file management table 90, and proceedsto S2201 if there is an unprocessed file name. Meanwhile, if there is nounprocessed file name, the migration processing program 14 ends theprocessing.

After completing the migration of all files from the migration sourceNAS apparatus 2 a to the migration destination NAS apparatus 2 b basedon the foregoing processing, by setting the IP address of the migrationsource NAS apparatus 2 a to the migration destination NAS apparatus 2 b,operation with the migration destination NAS apparatus 2 b can bestarted without having to change the setting of the NAS client 100.

In the second embodiment of the NAS apparatus migration method accordingto the present invention, the migration server 1 migrates files storedin the share directory of the migration source NAS apparatus 2 a to theshare directory of the migration destination NAS apparatus 2 b inchronological order of the update date and time. Thus, when repeatedlymigrating the NAS apparatus on a daily basis based on the migrationmethod of the present invention in a state of continuing the operationof the migration source NAS apparatus 2 a, migration of the files thatare updated daily will be postponed without having to define thecondition of the update date and time of the migration-target file, andthere is an effect of being able to quicken the migration progress. Inaddition, since the migration server 1 performs migration processing bybeing connected to the migration source NAS apparatus 2 a and themigration destination NAS apparatus 2 b as a single NAS client, there isno need to add a special function to the migration source NAS apparatus2 a and the migration destination NAS apparatus 2 b.

Third Embodiment

The third embodiment of the present invention is now explained withreference to FIG. 17 and FIG. 18.

FIG. 17 is a configuration example of a system schematically showing thestorage network system adopting the third embodiment of the presentinvention.

As shown in FIG. 17, the storage network system of this embodimentcomprises an operation terminal 101, at least one migration source NASapparatus 2 a, a storage apparatus 50 a connected to the migrationsource NAS apparatus 2 a, at least one migration destination NASapparatus 50 b, a storage apparatus 3 b connected to the migrationdestination NAS apparatus 2 b, a plurality of NAS clients 100 forimplementing file access to the migration source NAS apparatus 2 a, anda network 3 to which the copy source NAS apparatus 2 a, the copydestination NAS apparatus 2 b and the NAS client 100 are connected.

The operation terminal 101 is equipped with a keyboard 5, a mouse 6 andthe like, and is connected to the migration destination NAS apparatus 2b. The operation terminal 101 may be a standard personal computer withan operating system running thereon. The user uses the operationterminal 101 to edit the schedule table 30 stored in the migrationdestination NAS apparatus 2 b and start up the migration period estimateprocessing program 17 as described later.

The storage apparatuses 50 a, 50 b include at least one I/O port 51 forconnecting to the migration source NAS apparatus 2 a and the migrationdestination NAS apparatus 2 b, a controller 52 for performing control inthe storage apparatus, and at least one disk device 60 configuring atleast one volume 53. The volume 53 is a volume for providing a filesystem to the user of the NAS apparatuses 2 a, 2 b, and stores files andtheir attribute information.

FIG. 18 is a diagram schematically showing the configuration example ofthe migration destination NAS apparatus 2 b in the third embodiment. Asshown in FIG. 18, the migration destination NAS apparatus 2 b comprisesa memory 70, a CPU 71, at least one I/O port 72 for connecting to thestorage apparatuses 50 a, 50 b, a management port 73, and an internalbus 74 for connecting the foregoing components 70 to 73. The memory 70stores a communication control processing program 75 for communicatingwith a communication protocol of the network 3, an NFS/CIFS serverprocessing program 76 that provides a function for the host computer toaccess the volumes provided by the migration destination NAS apparatus 2b, an NFS/CIFS client processing program 78 for accessing the filesystem provided by the migration source NAS apparatus 2 a, a migrationprocessing program 14 for implementing the NAS apparatus migrationmethod of the present invention, a migration processing startupprocessing program 15 for starting up the migration processing program14, and a migration period estimate processing program 17 for estimatingthe migration period. The CPU 71 executes these programs. The memory 70additionally stores a schedule table 30 storing a schedule for themigration processing startup processing program 15 to start up themigration processing program 14, a NAS management table 20 to be used bythe migration processing program 14, and an execution result log 40 foroutputting the migration result of the migration processing program 14.

In the third embodiment, the migration destination NAS apparatus 2 bmounts the file system provided by the migration source NAS apparatus 2a, and the migration processing program 14 of the migration destinationNAS apparatus 2 b implements the migration processing. Since theprocessing contents of the migration processing startup processingprogram 15, the migration processing program 14, and the migrationperiod estimate processing program 17 are the same as the firstembodiment, the explanation thereof is omitted.

In the third embodiment of the NAS apparatus migration method accordingto the present invention, the migration destination NAS apparatus 2 bmigrates files, other than the files that were updated from a certainspecific date and time to the migration start date and time among thefiles stored in the share directory of the migration source NASapparatus 2 a, to the share directory of the migration destination NASapparatus 2 b. Moreover, the migration performance is calculated basedon the file size of the migrated file and the time required for themigration, and the time required for migrating the non-migrated files iscalculated based on the file size of the non-migrated files and themigration performance. Thus, the same effect as the first embodiment canbe obtained. In addition, there is no need to provide an apparatus otherthan the NAS apparatus for performing the migration processing.

Fourth Embodiment

The fourth embodiment of the present invention is now explained withreference to FIG. 19. Since the system configuration is the same as thethird embodiment, the explanation thereof is omitted.

FIG. 19 is a diagram schematically showing a configuration example ofthe migration destination NAS apparatus 2 b in the fourth embodiment. Asshown in FIG. 19, the migration destination NAS apparatus 2 b comprisesa memory 70, a CPU 71, at least one I/O port 72 for connecting to thestorage apparatuses 50 a, 50 b, a management port 73, and an internalbus 74 for connecting the foregoing components 70 to 73. The memory 70stores a communication control processing program 75 for communicatingwith a communication protocol of the network 3, an NFS/CIFS serverprocessing program 76 that provides a function for the host computer toaccess the volumes provided by the migration destination NAS apparatus 2b, an NFS/CIFS client processing program 78 for accessing the filesystem provided by the migration source NAS apparatus 2 a, a migrationprocessing program 14 for implementing the NAS apparatus migrationmethod of the present invention, and a migration processing startupprocessing program 15 for starting up the migration processing program14. The CPU 71 executes these programs. The memory 70 additionallystores a schedule table 30 storing a schedule for the migrationprocessing startup processing program 15 to start up the migrationprocessing program 14, a NAS management table 20 to be used by themigration processing program 14, an execution result log 40 foroutputting the migration result of the migration processing program 14,and a file management table 90 for storing a list of files stored in theshare directory of the migration source NAS apparatus 2 a.

In the fourth embodiment, as with the third embodiment, the migrationdestination NAS apparatus 2 b mounts the file system provided by themigration source NAS apparatus 2 a, and the migration processing program14 of the migration destination NAS apparatus 2 b implements themigration processing. Since the processing contents of the migrationprocessing startup processing program 15 and the migration processingprogram 14 are the same as the second embodiment, the explanationthereof is omitted.

In the fourth embodiment of the NAS apparatus migration method accordingto the present invention, the migration destination NAS apparatus 2 bmigrates files stored in the share directory of the migration source NASapparatus 2 a to the share directory of the migration destination NASapparatus 2 b in chronological order of the update date and time. Thus,when repeatedly migrating the NAS apparatus on a daily basis based onthe migration method of the present invention in a state of continuingthe operation of the migration source NAS apparatus 2 a, migration ofthe files that are updated daily will be postponed without having todefine the condition of the update date and time of the migration-targetfile, and there is an effect of being able to quicken the migrationprogress. In addition, as with the third embodiment, there is no need toprovide an apparatus other than the NAS apparatus for performing themigration processing.

According to the NAS apparatus migration method of the present inventionexplained in the foregoing first to fourth embodiments, only the filesthat are not updated from a certain specific time up to theimplementation of the migration processing are migrated in the migrationof the NAS apparatus in a state of continuing the operation of themigration source NAS apparatus. Moreover, a file with old update dateand time is preferentially migrated. Thus, even if numerous files areupdated in the migration source NAS apparatus, the migration processingcan be sped up. Moreover, the migration performance is calculated basedon the file size of the migrated file and the time required for themigration, and the time required for migrating the non-migrated files iscalculated based on the file size of the non-migrated files and themigration performance. Thus, it is possible to estimate the timerequired for migrating the non-migrated files (files excluded frommigration). Further, since migration processing is implemented whilecontinuing the operation of the migration source NAS apparatus, thelatest files will constantly be stored in the migration source NASapparatus. Thus, the operation of the migration source NAS apparatus canbe easily resumed even if the migration processing is unsuccessful dueto a failure or the like.

1. A file migration method of an information system, the informationsystem including a plurality of Network Attached Storage (NAS) systems,and a computer for reading and writing a plurality of files stored inthe NAS systems, wherein the file migration method comprises: executingsteps of file migration startup processing; executing steps of filemigration processing; and executing steps of file migration terminationprocessing to be executed after execution of the file migrationprocessing, wherein the file migration startup processing comprises: astep of providing a management table which indicates a plurality ofrelationships between a source system and a destination system; a stepof identifying a first NAS system of the NAS systems as the sourcesystem of a file migration based on the management table; and a step ofidentifying a second NAS system of the NAS systems as the destinationsystem of the file migration based on the management table, wherein thefile migration processing comprises: a step of acquiring and storingfirst attribute information including file names, update timeinformation and a Write Only Read Many setting concerning a plurality offiles stored in a designated directory of the first NAS system; a stepof acquiring and storing second attribute information including filenames and update time information concerning a plurality of files storedin the second NAS system; a step of identifying a file to be copied fromthe first NAS system to the second NAS system based on the differencebetween the stored first attribute information and second attributeinformation, and a prescribed rule which preferentially identifies afile with old update time information of the first attribute informationas a file to be copied; a step of determining whether the identifiedfile is set Write Only Read Many or not; and a step of copying theidentified file from the first NAS system to the second NAS system whenthe identified file is not set Write Only Read Many, and wherein thefile migration termination processing comprises: a step of acquiring andstoring third attribute information including file names and update timeinformation concerning a plurality of files to be stored in a designateddirectory of the first NAS system; a step of acquiring and storingfourth attribute information including file names and update timeinformation concerning a plurality of files stored in the second NASsystem based on the file migration processing; and a step of identifyingand copying a file to be copied from the first NAS system to the secondNAS system based on the difference between the stored third attributeinformation and fourth attribute information.
 2. The file migrationmethod of an information system according to claim 1, wherein, based ona first time obtained by subtracting a predetermined migration exclusionupdate period from an execution time of the file migration processingand the update time information of the first attribute information, theprescribed rule identifies a file updated after the first time as a copyinhibition target.
 3. The file migration method of an information systemaccording to claim 1, wherein the step of copying the identified filefrom the first NAS system to the second NAS system further includes astep of setting a Write Only Read Many to the file copied to the secondNAS system according to information concerning the Write Only Read Manysetting included in the first attribute information.
 4. The filemigration method of an information system according to claim 3, whereinthe file migration method further comprises: a step of identifying afile set with Write Only Read Many from the second attributeinformation; and a step of excluding the identified file set with WriteOnly Read Many from an acquisition target of the first attributeinformation.
 5. The file migration method of an information systemaccording to claim 1, wherein the step of copying the identified filefrom the first NAS system to the second NAS system includes a step ofrecording the copying time and file size of the copied file; and whereinthe file migration method further comprises: a step of identifying thetotal file size concerning files to be copied before the end ofmigration among a plurality of files stored in a designated directoryand below of the first NAS system; and a step of providing migrationperiod information based on the copying time, the file size and thetotal file size.
 6. The file migration method of an information systemaccording to claim 1, wherein the file migration processing and filemigration termination processing are processed with the second NASsystem, or a migration computer connected to the first NAS system andthe second NAS system.
 7. A migration computer coupled to a plurality ofNetwork Attached Storage (NAS) systems and a computer, the migrationcomputer for migrating a plurality of files stored in a designateddirectory and below of a first NAS system of the plurality of NASsystems to a second NAS system of the plurality of systems, themigration computer comprising: a processor; an I/O port; and a storagearea, wherein the storage area stores programs which cause the processorto execute file migration startup processing, file startup processing,and file migration termination processing, the file migrationtermination processing to be executed after the execution of the filemigration processing, wherein the file migration startup processingcomprises: a step of providing a management table which indicates aplurality of relationships between a source system and a destinationsystem; a step of identifying the first NAS system as the source systemof a file migration based on the management table; and a step ofidentifying the second NAS system as the destination system of the filemigration based on the management table, wherein the storage areafurther stores: first attribute information including file names andupdate time information concerning a plurality of files to be stored ina designated directory of the first NAS system; second attributeinformation including file names and update time information concerninga plurality of files stored in the second NAS system; and a program forcausing the processor to identify a file to be copied from the first NASsystem to the second NAS system based on the difference between thestored first attribute information and second attribute information, anda prescribed rule which preferentially identifies a file with old updatetime information of the first attribute information as a file to becopied, determines whether the identified file is set Write Only ReadMany or not, and copy the file identified with the I/O port when theidentified file is not set Write Only Read Many, wherein the copying ofthe identified file from the first NAS system to the second NAS systemfurther includes the setting of a Write Only Read Many to the filecopied to the second NAS system according to information concerning theWrite Only Read Many setting included in the first attributeinformation.
 8. The migration computer according to claim 7, wherein,based on a first time obtained by subtracting a predetermined migrationexclusion update period from the processing time of the program and theupdate time information of the first attribute information, theprescribed rule identifies a file updated after the first time as a copyinhibition target.
 9. The migration computer according to claim 7,wherein the program further: identifies a file set with Write Only ReadMany from the second attribute information; and excludes the identifiedfile set with Write Only Read Many from the acquisition target of thefirst attribute information.
 10. The migration computer according toclaim 7, wherein the copying of the identified file from the first NASsystem to the second NAS system of the program includes the recordingprocessing of the copying time and file size of the copied file; andwherein the program further: identifies the total file size concerningfiles to be copied before the end of migration among a plurality offiles stored in a designated directory and below of the first NASsystem; and provides migration period information based on the copyingtime, the file size and the total file size.
 11. A program of amigration computer, wherein the program causes the migration computerto: execute steps of file migration startup processing; execute steps offile migration processing; and execute steps of file migrationtermination processing executed after execution of the file migrationprocessing, wherein the file migration startup processing causes themigration computer to: provide a management table which indicates aplurality of relationships between a source system and a destinationsystem; identify a first NAS system of the NAS systems as the sourcesystem of a file migration based on the management table; and identify asecond NAS system of the NAS systems as the destination system of thefile migration based on the management table, wherein the file migrationprocessing causes the migration computer to: acquire and store firstattribute information including file names and update time informationconcerning a plurality of files to be stored in a designated directoryof a first Network Attached Storage (NAS) system coupled to themigration computer; acquire and store second attribute informationincluding file names and update time information concerning a pluralityof files stored in a second NAS system coupled to the migrationcomputer; identify a file to be copied from the first NAS system to thesecond NAS system based on the difference between the stored firstattribute information and second attribute information, and a prescribedrule which preferentially identifies a file with old update timeinformation of the first attribute information as a file to be copied;determine whether the identified file is set Write Only Read Many ornot; copy the identified file from the first NAS system to the secondNAS system when the identified file is not set Write Only Read Many,wherein the file migration termination processing causes the computerto: acquire and store third attribute information including file namesand update time information concerning a plurality of files to be storedin a designated directory of the first NAS system; acquire and storefourth attribute information including file names and update timeinformation concerning a plurality of files stored in the second NASsystem; and identify and copy one or more files to be copied from thefirst NAS system to the second NAS system based on the differencebetween the stored third attribute information and fourth attributeinformation, and wherein, based on a first time obtained by subtractinga predetermined migration exclusion update period from an execution timeof the file migration processing and the update time information of thefirst attribute information, the prescribed rule identifies a fileupdated after the first time as a copy inhibition target.
 12. Theprogram of a migration computer according to claim 11, wherein thecopying of the identified file from the first NAS system to the secondNAS system further includes the setting of a Write Only Read Many to thefile copied to the second NAS system.
 13. The program of a migrationcomputer according to claim 11, wherein the program further causes themigration computer to: identify a file set with Write Only Read Manyfrom the second attribute information; and execute the identified fileset with Write Only Read Many from the acquisition target of the firstattribute information.
 14. The program of a migration computer accordingto claim 11, wherein the copying of the identified file from the firstNAS system to the second NAS system of the program includes therecording of the copying time and file size of the copied file; andwherein the program further causes the migration computer to: identifythe total file size concerning files to be copied before the end ofmigration among a plurality of files stored in a designated directory ofthe first NAS system with the first attribute information; and providemigration period information based on the copying time, the file sizeand the total file size.